apertis-update-manager-automount: Fix unknown key setup

The bundle generation with an unknown key doesn't display correctly.
Add a command to retrieve the `key0.key` file from gitlab.apertis.org.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

test-cases/apertis-update-manager-automount.yaml

@@ -21,15 +21,15 @@ metadata:
     - "The static encrypted update file should be copied to the second flash drive using the name 'static-update.bundle.enc'."
     - "A third Fat32 USB flash drive, preloaded with the encrypted update bundle with unknown key at the root of the disk"
     - "This can be generated from the encrypted update bundle using one of the key used for encryption (saved to key0.key) and the following commands:"
-    - |
-        $ echo -n "wrong key" > tmp.key
-        $ BUNDLE=<encrypted-static-update-filename>.delta.enc
-        $ cp $BUNDLE $BUNDLE.badkey
-        $ sudo udisksctl loop-setup -f $BUNDLE.badkey
-        $ sudo cryptsetup luksChangeKey --key-file=key0.key --key-slot=0 /dev/loop0 tmp.key
-        $ for i in {1..7} ; do sudo cryptsetup luksKillSlot --key-file=tmp.key /dev/loop0 $i ; done
-        $ sudo udisksctl loop-delete -b /dev/loop0
-    - "The static encrypted update file with unknown key should be copied to the third flash drive using the name 'static-update.bundle.enc'."
+    - $ wget -O key0.key https://gitlab.apertis.org/infrastructure/apertis-image-recipes/-/raw/apertis/v2021dev3/overlays/apertis-update-manager/usr/share/apertis-update-manager
+    - $ echo -n "wrong key" > tmp.key
+    - $ BUNDLE=<encrypted-static-update-filename>.delta.enc
+    - $ cp $BUNDLE $BUNDLE.badkey
+    - $ sudo udisksctl loop-setup -f $BUNDLE.badkey
+    - $ sudo cryptsetup luksChangeKey --key-file=key0.key --key-slot=0 /dev/loop0 tmp.key
+    - $ for i in {1..7} ; do sudo cryptsetup luksKillSlot --key-file=tmp.key /dev/loop0 $i ; done
+    - $ sudo udisksctl loop-delete -b /dev/loop0
+    - "The static encrypted update file with unknown key ($BUNDLE.badkey) should be copied to the third flash drive using the name 'static-update.bundle.enc'."
     - "A PC must be connected to DUT serial port"
 
   expected: